完全可以.
例如：
1 By yesterday we were ready to set out for Tibet on our first trip there.
2 By the time she was 25,she was a mother of three children.
(注意,這個(gè)過(guò)去時(shí)往往局限于be動(dòng)詞)
但：1 By yesterday,they had left for Tibet on their first trip.
2 By the time she was 25,she had neen married for 6 years and had three children.(注意,這里的have也用一般過(guò)去時(shí)had,因?yàn)閔ave強(qiáng)調(diào)的是狀態(tài),不是動(dòng)作.)